Systems and methods of user localization

ABSTRACT

Systems and methods are disclosed in which a playback device transmits a first sound signal including a predetermined waveform. In one example, the playback device receives a second sound signal including at least one reflection of the first sound signal. The second sound signal is processed to determine a location of a person relative to the playback device, and a characteristic of audio reproduction by the playback device is selected, based on the determined location of the person.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/948,609, filed Sep. 24, 2020, which is a continuation ofU.S. application Ser. No. 16/353,774, filed Mar. 14, 2019, now U.S. Pat.No. 10,791,396, which is a continuation of U.S. application Ser. No.16/149,992, filed on Oct. 2, 2018, now U.S. Pat. No. 10,277,981, whichare incorporated herein by reference in their entireties.

FIELD OF THE DISCLOSURE

The present disclosure is related to consumer goods and, moreparticularly, to methods, systems, products, features, services, andother elements directed to media playback or some aspect thereof.

BACKGROUND

Options for accessing and listening to digital audio in an out-loudsetting were limited until in 2002, when SONOS, Inc. began developmentof a new type of playback system. Sonos then filed one of its firstpatent applications in 2003, entitled “Method for Synchronizing AudioPlayback between Multiple Networked Devices,” and began offering itsfirst media playback systems for sale in 2005. The Sonos Wireless HomeSound System enables people to experience music from many sources viaone or more networked playback devices. Through a software controlapplication installed on a controller (e.g., smartphone, tablet,computer, voice input device), one can play what she wants in any roomhaving a networked playback device. Media content (e.g., songs,podcasts, video sound) can be streamed to playback devices such thateach room with a playback device can play back corresponding differentmedia content. In addition, rooms can be grouped together forsynchronous playback of the same media content, and/or the same mediacontent can be heard in all rooms synchronously.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and advantages of the presently disclosed technologymay be better understood with regard to the following description,appended claims, and accompanying drawings, as listed below. A personskilled in the relevant art will understand that the features shown inthe drawings are for purposes of illustrations, and variations,including different and/or additional features and arrangements thereof,are possible.

FIG. 1A is a partial cutaway view of an environment having a mediaplayback system configured in accordance with aspects of the disclosedtechnology.

FIG. 1B is a schematic diagram of the media playback system of FIG. 1Aand one or more networks.

FIG. 1C is a block diagram of a playback device.

FIG. 1D is a block diagram of a playback device.

FIG. 1E is a block diagram of a network microphone device.

FIG. 1F is a block diagram of a network microphone device.

FIG. 1G is a block diagram of a playback device.

FIG. 1H is a partially schematic diagram of a control device.

FIGS. 1 -I through 1L are schematic diagrams of corresponding mediaplayback system zones.

FIG. 1M is a schematic diagram of media playback system areas.

FIG. 2A is a front isometric view of a playback device configured inaccordance with aspects of the disclosed technology.

FIG. 2B is a front isometric view of the playback device of FIG. 3Awithout a grille.

FIG. 2C is an exploded view of the playback device of FIG. 2A.

FIG. 3A is a front view of a network microphone device configured inaccordance with aspects of the disclosed technology.

FIG. 3B is a side isometric view of the network microphone device ofFIG. 3A.

FIG. 3C is an exploded view of the network microphone device of FIGS. 3Aand 3B.

FIG. 3D is an enlarged view of a portion of FIG. 3B.

FIG. 3E is a block diagram of the network microphone device of FIGS.3A-3D

FIG. 3F is a schematic diagram of an example voice input.

FIG. 4 is a plan view of a playback environment.

FIG. 5 is a block diagram of a playback device.

FIG. 6 is a flow diagram representing a method for selecting acharacteristic of audio reproduction based on a determined location of aperson.

FIG. 7 is a graph of data output by a multi-stage noise-shaping (MASH)modulator.

FIG. 8 is a schematic diagram depicting two microphones receivingreflections of a sound signal.

FIG. 9 is a flow diagram representing a method for configuring aplayback device.

FIG. 10 is a schematic representation of a data structure for storingcalibration data.

FIG. 11 is a plan view of a playback environment.

The drawings are for the purpose of illustrating example embodiments,but those of ordinary skill in the art will understand that thetechnology disclosed herein is not limited to the arrangements and/orinstrumentality shown in the drawings.

DETAILED DESCRIPTION I. Overview

Embodiments described herein relate to selection of audio reproductioncharacteristics by a playback device based a location of a person. Forexample, it may be beneficial to adjust audio reproduction based on thelocation of a listener so that the audio experience is improved for thatlocation. However, it can be difficult for a playback system todetermine a location of a person within the playback environment.

In some embodiments, for example, a playback device transmits a firstsound signal including a predetermined waveform. The playback devicereceives a second sound signal including at least one reflection of thefirst sound signal. The second sound signal is processed to determine alocation of a person relative to the playback device, and acharacteristic of audio reproduction by the playback device is selected,based on the determined location of the person.

Thus, a person can be located using sound signals and audio reproductionadjusted accordingly to provide an improved audio experience.

In some embodiments, a playback device comprises a transducer configuredto generate audio signals; a microphone; and a processing system. Thetransducer is arranged to transmit a first sound signal comprising apredetermined waveform. The microphone is arranged to receive a secondsound signal comprising at least one reflection of the first ultrasoundsignal. The processing system is arranged to: determine a location of aperson relative to the playback device based on the second sound signal;and set a characteristic of audio reproduction by the playback devicebased on the determined location of the person.

In some embodiment, a non-transitory computer readable medium comprisescomputer program instructions which, when executed by a processingsystem, instruct the processing system to: cause an electroacoustictransducer in a playback device to transmit a first sound signalcomprising a predetermined waveform; cause a microphone in the playbackdevice to receive a second sound signal comprising at least onereflection of the first sound signal; process the second sound signal todetermine a location of a person relative to the playback device; andset a characteristic of audio reproduction by the playback device basedon the determined location of the person.

While some examples described herein may refer to functions performed bygiven actors such as “users,” “listeners,” and/or other entities, itshould be understood that this is for purposes of explanation only. Theclaims should not be interpreted to require action by any such exampleactor unless explicitly required by the language of the claimsthemselves.

In the Figures, identical reference numbers identify generally similar,and/or identical, elements. To facilitate the discussion of anyparticular element, the most significant digit or digits of a referencenumber refers to the Figure in which that element is first introduced.For example, element 110 a is first introduced and discussed withreference to FIG. 1A. Many of the details, dimensions, angles and otherfeatures shown in the Figures are merely illustrative of particularembodiments of the disclosed technology. Accordingly, other embodimentscan have other details, dimensions, angles and features withoutdeparting from the spirit or scope of the disclosure. In addition, thoseof ordinary skill in the art will appreciate that further embodiments ofthe various disclosed technologies can be practiced without several ofthe details described below.

II. Suitable Operating Environment

FIG. 1A is a partial cutaway view of a media playback system 100distributed in an environment 101 (e.g., a house). The media playbacksystem 100 comprises one or more playback devices 110 (identifiedindividually as playback devices 110 a-n), one or more networkmicrophone devices (“NMDs”), 120 (identified individually as NMDs 120a-c), and one or more control devices 130 (identified individually ascontrol devices 130 a and 130 b).

As used herein the term “playback device” can generally refer to anetwork device configured to receive, process, and output data of amedia playback system. For example, a playback device can be a networkdevice that receives and processes audio content. In some embodiments, aplayback device includes one or more transducers or speakers powered byone or more amplifiers. In other embodiments, however, a playback deviceincludes one of (or neither of) the speaker and the amplifier. Forinstance, a playback device can comprise one or more amplifiersconfigured to drive one or more speakers external to the playback devicevia a corresponding wire or cable.

Moreover, as used herein the term NMD (i.e., a “network microphonedevice”) can generally refer to a network device that is configured foraudio detection. In some embodiments, an NMD is a stand-alone deviceconfigured primarily for audio detection. In other embodiments, an NMDis incorporated into a playback device (or vice versa).

The term “control device” can generally refer to a network deviceconfigured to perform functions relevant to facilitating user access,control, and/or configuration of the media playback system 100.

Each of the playback devices 110 is configured to receive audio signalsor data from one or more media sources (e.g., one or more remoteservers, one or more local devices) and play back the received audiosignals or data as sound. The one or more NMDs 120 are configured toreceive spoken word commands, and the one or more control devices 130are configured to receive user input. In response to the received spokenword commands and/or user input, the media playback system 100 can playback audio via one or more of the playback devices 110. In certainembodiments, the playback devices 110 are configured to commenceplayback of media content in response to a trigger. For instance, one ormore of the playback devices 110 can be configured to play back amorning playlist upon detection of an associated trigger condition(e.g., presence of a user in a kitchen, detection of a coffee machineoperation). In some embodiments, for example, the media playback system100 is configured to play back audio from a first playback device (e.g.,the playback device 100 a) in synchrony with a second playback device(e.g., the playback device 100 b). Interactions between the playbackdevices 110, NMDs 120, and/or control devices 130 of the media playbacksystem 100 configured in accordance with the various embodiments of thedisclosure are described in greater detail below with respect to FIGS.1B-1M.

In the illustrated embodiment of FIG. 1A, the environment 101 comprisesa household having several rooms, spaces, and/or playback zones,including (clockwise from upper left) a master bathroom 101 a, a masterbedroom 101 b, a second bedroom 101 c, a family room or den 101 d, anoffice 101 e, a living room 101 f, a dining room 101 g, a kitchen 101 h,and an outdoor patio 101 i. While certain embodiments and examples aredescribed below in the context of a home environment, the technologiesdescribed herein may be implemented in other types of environments. Insome embodiments, for example, the media playback system 100 can beimplemented in one or more commercial settings (e.g., a restaurant,mall, airport, hotel, a retail or other store), one or more vehicles(e.g., a sports utility vehicle, bus, car, a ship, a boat, an airplane),multiple environments (e.g., a combination of home and vehicleenvironments), and/or another suitable environment where multi-zoneaudio may be desirable.

The media playback system 100 can comprise one or more playback zones,some of which may correspond to the rooms in the environment 101. Themedia playback system 100 can be established with one or more playbackzones, after which additional zones may be added, or removed to form,for example, the configuration shown in FIG. 1A. Each zone may be givena name according to a different room or space such as the office 101 e,master bathroom 101 a, master bedroom 101 b, the second bedroom 101 c,kitchen 101 h, dining room 101 g, living room 101 f, and/or the balcony101 i. In some aspects, a single playback zone may include multiplerooms or spaces. In certain aspects, a single room or space may includemultiple playback zones.

In the illustrated embodiment of FIG. 1A, the master bathroom 101 a, thesecond bedroom 101 c, the office 101 e, the living room 101 f, thedining room 101 g, the kitchen 101 h, and the outdoor patio 101 i eachinclude one playback device 110, and the master bedroom 101 b and theden 101 d include a plurality of playback devices 110. In the masterbedroom 101 b, the playback devices 110 l and 110 m may be configured,for example, to play back audio content in synchrony as individual onesof playback devices 110, as a bonded playback zone, as a consolidatedplayback device, and/or any combination thereof. Similarly, in the den101 d, the playback devices 110 h-j can be configured, for instance, toplay back audio content in synchrony as individual ones of playbackdevices 110, as one or more bonded playback devices, and/or as one ormore consolidated playback devices. Additional details regarding bondedand consolidated playback devices are described below with respect toFIGS. 1B, 1E, and 1I-1M.

In some aspects, one or more of the playback zones in the environment101 may each be playing different audio content. For instance, a usermay be grilling on the patio 101 i and listening to hip hop music beingplayed by the playback device 110 c while another user is preparing foodin the kitchen 101 h and listening to classical music played by theplayback device 110 b. In another example, a playback zone may play thesame audio content in synchrony with another playback zone. Forinstance, the user may be in the office 101 e listening to the playbackdevice 110 f playing back the same hip hop music being played back byplayback device 110 c on the patio 101 i. In some aspects, the playbackdevices 110 c and 110 f play back the hip hop music in synchrony suchthat the user perceives that the audio content is being playedseamlessly (or at least substantially seamlessly) while moving betweendifferent playback zones. Additional details regarding audio playbacksynchronization among playback devices and/or zones can be found, forexample, in U.S. Pat. No. 8,234,395 entitled, “System and method forsynchronizing operations among a plurality of independently clockeddigital data processing devices,” which is incorporated herein byreference in its entirety.

a. Suitable Media Playback System

FIG. 1B is a schematic diagram of the media playback system 100 and acloud network 102. For ease of illustration, certain devices of themedia playback system 100 and the cloud network 102 are omitted fromFIG. 1B. One or more communication links 103 (referred to hereinafter as“the links 103”) communicatively couple the media playback system 100and the cloud network 102.

The links 103 can comprise, for example, one or more wired networks, oneor more wireless networks, one or more wide area networks (WAN), one ormore local area networks (LAN), one or more personal area networks(PAN), one or more telecommunication networks (e.g., one or more GlobalSystem for Mobiles (GSM) networks, Code Division Multiple Access (CDMA)networks, Long-Term Evolution (LTE) networks, 5G communication networknetworks, and/or other suitable data transmission protocol networks),etc. The cloud network 102 is configured to deliver media content (e.g.,audio content, video content, photographs, social media content) to themedia playback system 100 in response to a request transmitted from themedia playback system 100 via the links 103. In some embodiments, thecloud network 102 is further configured to receive data (e.g. voiceinput data) from the media playback system 100 and correspondinglytransmit commands and/or media content to the media playback system 100.

The cloud network 102 comprises computing devices 106 (identifiedseparately as a first computing device 106 a, a second computing device106 b, and a third computing device 106 c). The computing devices 106can comprise individual computers or servers, such as, for example, amedia streaming service server storing audio and/or other media content,a voice service server, a social media server, a media playback systemcontrol server, etc. In some embodiments, one or more of the computingdevices 106 comprise modules of a single computer or server. In certainembodiments, one or more of the computing devices 106 comprise one ormore modules, computers, and/or servers. Moreover, while the cloudnetwork 102 is described above in the context of a single cloud network,in some embodiments the cloud network 102 comprises a plurality of cloudnetworks comprising communicatively coupled computing devices.Furthermore, while the cloud network 102 is shown in FIG. 1B as havingthree of the computing devices 106, in some embodiments, the cloudnetwork 102 comprises fewer (or more) than three computing devices 106.

The media playback system 100 is configured to receive media contentfrom the networks 102 via the links 103. The received media content cancomprise, for example, a Uniform Resource Identifier (URI) and/or aUniform Resource Locator (URL). For instance, in some examples, themedia playback system 100 can stream, download, or otherwise obtain datafrom a URI or a URL corresponding to the received media content. Anetwork 104 communicatively couples the links 103 and at least a portionof the devices (e.g., one or more of the playback devices 110, NMDs 120,and/or control devices 130) of the media playback system 100. Thenetwork 104 can include, for example, a wireless network (e.g., a WiFinetwork, a Bluetooth, a Z-Wave network, a ZigBee, and/or other suitablewireless communication protocol network) and/or a wired network (e.g., anetwork comprising Ethernet, Universal Serial Bus (USB), and/or anothersuitable wired communication). As those of ordinary skill in the artwill appreciate, as used herein, “WiFi” can refer to several differentcommunication protocols including, for example, Institute of Electricaland Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, 802.11ad, 802.11af, 802.11ah, 802.11ai, 802.11aj, 802.11aq,802.11ax, 802.11ay, 802.15, etc. transmitted at 2.4 Gigahertz (GHz), 5GHz, and/or another suitable frequency.

In some embodiments, the network 104 comprises a dedicated communicationnetwork that the media playback system 100 uses to transmit messagesbetween individual devices and/or to transmit media content to and frommedia content sources (e.g., one or more of the computing devices 106).In certain embodiments, the network 104 is configured to be accessibleonly to devices in the media playback system 100, thereby reducinginterference and competition with other household devices. In otherembodiments, however, the network 104 comprises an existing householdcommunication network (e.g., a household WiFi network). In someembodiments, the links 103 and the network 104 comprise one or more ofthe same networks. In some aspects, for example, the links 103 and thenetwork 104 comprise a telecommunication network (e.g., an LTE network,a 5G network). Moreover, in some embodiments, the media playback system100 is implemented without the network 104, and devices comprising themedia playback system 100 can communicate with each other, for example,via one or more direct connections, PANs, telecommunication networks,and/or other suitable communication links.

In some embodiments, audio content sources may be regularly added orremoved from the media playback system 100. In some embodiments, forexample, the media playback system 100 performs an indexing of mediaitems when one or more media content sources are updated, added to,and/or removed from the media playback system 100. The media playbacksystem 100 can scan identifiable media items in some or all foldersand/or directories accessible to the playback devices 110, and generateor update a media content database comprising metadata (e.g., title,artist, album, track length) and other associated information (e.g.,URIs, URLs) for each identifiable media item found. In some embodiments,for example, the media content database is stored on one or more of theplayback devices 110, network microphone devices 120, and/or controldevices 130.

In the illustrated embodiment of FIG. 1B, the playback devices 110 l and110 m comprise a group 107 a. The playback devices 110 l and 110 m canbe positioned in different rooms in a household and be grouped togetherin the group 107 a on a temporary or permanent basis based on user inputreceived at the control device 130 a and/or another control device 130in the media playback system 100. When arranged in the group 107 a, theplayback devices 110 l and 110 m can be configured to play back the sameor similar audio content in synchrony from one or more audio contentsources. In certain embodiments, for example, the group 107 a comprisesa bonded zone in which the playback devices 110 l and 110 m compriseleft audio and right audio channels, respectively, of multi-channelaudio content, thereby producing or enhancing a stereo effect of theaudio content. In some embodiments, the group 107 a includes additionalplayback devices 110. In other embodiments, however, the media playbacksystem 100 omits the group 107 a and/or other grouped arrangements ofthe playback devices 110. Additional details regarding groups and otherarrangements of playback devices are described in further detail belowwith respect to FIGS. 1 -I through 1-M.

The media playback system 100 includes the NMDs 120 a and 120 b, eachcomprising one or more microphones configured to receive voiceutterances from a user. In the illustrated embodiment of FIG. 1B, theNMD 120 a is a standalone device and the NMD 120 b is integrated intothe playback device 110 n. The NMD 120 a, for example, is configured toreceive voice input 121 from a user 123. In some embodiments, the NMD120 a transmits data associated with the received voice input 121 to avoice assistant service (VAS) configured to (i) process the receivedvoice input data and (ii) transmit a corresponding command to the mediaplayback system 100. In some aspects, for example, the computing device106 c comprises one or more modules and/or servers of a VAS (e.g., a VASoperated by one or more of SONOS®, AMAZON®, GOOGLE® APPLE®, MICROSOFT®).The computing device 106 c can receive the voice input data from the NMD120 a via the network 104 and the links 103. In response to receivingthe voice input data, the computing device 106 c processes the voiceinput data (i.e., “Play Hey Jude by The Beatles”), and determines thatthe processed voice input includes a command to play a song (e.g., “HeyJude”). The computing device 106 c accordingly transmits commands to themedia playback system 100 to play back “Hey Jude” by the Beatles from asuitable media service (e.g., via one or more of the computing devices106) on one or more of the playback devices 110.

b. Suitable Playback Devices

FIG. 1C is a block diagram of the playback device 110 a comprising aninput/output 111. The input/output 111 can include an analog I/O 111 a(e.g., one or more wires, cables, and/or other suitable communicationlinks configured to carry analog signals) and/or a digital I/O 111 b(e.g., one or more wires, cables, or other suitable communication linksconfigured to carry digital signals). In some embodiments, the analogI/O 111 a is an audio line-in input connection comprising, for example,an auto-detecting 3.5 mm audio line-in connection. In some embodiments,the digital I/O 111 b comprises a Sony/Philips Digital Interface Format(S/PDIF) communication interface and/or cable and/or a Toshiba Link(TOSLINK) cable. In some embodiments, the digital I/O 111 b comprises aHigh-Definition Multimedia Interface (HDMI) interface and/or cable. Insome embodiments, the digital I/O 111 b includes one or more wirelesscommunication links comprising, for example, a radio frequency (RF),infrared, WiFi, Bluetooth, or another suitable communication protocol.In certain embodiments, the analog I/O 111 a and the digital I/O 111 bcomprise interfaces (e.g., ports, plugs, jacks) configured to receiveconnectors of cables transmitting analog and digital signals,respectively, without necessarily including cables.

The playback device 110 a, for example, can receive media content (e.g.,audio content comprising music and/or other sounds) from a local audiosource 105 via the input/output 111 (e.g., a cable, a wire, a PAN, aBluetooth connection, an ad hoc wired or wireless communication network,and/or another suitable communication link). The local audio source 105can comprise, for example, a mobile device (e.g., a smartphone, atablet, a laptop computer) or another suitable audio component (e.g., atelevision, a desktop computer, an amplifier, a phonograph, a Blu-rayplayer, a memory storing digital media files). In some aspects, thelocal audio source 105 includes local music libraries on a smartphone, acomputer, a networked-attached storage (NAS), and/or another suitabledevice configured to store media files. In certain embodiments, one ormore of the playback devices 110, NMDs 120, and/or control devices 130comprise the local audio source 105. In other embodiments, however, themedia playback system omits the local audio source 105 altogether. Insome embodiments, the playback device 110 a does not include aninput/output 111 and receives all audio content via the network 104.

The playback device 110 a further comprises electronics 112, a userinterface 113 (e.g., one or more buttons, knobs, dials, touch-sensitivesurfaces, displays, touchscreens), and one or more transducers 114(referred to hereinafter as “the transducers 114”). The electronics 112is configured to receive audio from an audio source (e.g., the localaudio source 105) via the input/output 111, one or more of the computingdevices 106 a-c via the network 104 (FIG. 1B)), amplify the receivedaudio, and output the amplified audio for playback via one or more ofthe transducers 114. In some embodiments, the playback device 110 aoptionally includes one or more microphones 115 (e.g., a singlemicrophone, a plurality of microphones, a microphone array) (hereinafterreferred to as “the microphones 115”). In certain embodiments, forexample, the playback device 110 a having one or more of the optionalmicrophones 115 can operate as an NMD configured to receive voice inputfrom a user and correspondingly perform one or more operations based onthe received voice input.

In the illustrated embodiment of FIG. 1C, the electronics 112 compriseone or more processors 112 a (referred to hereinafter as “the processors112 a”), memory 112 b, software components 112 c, a network interface112 d, one or more audio processing components 112 g (referred tohereinafter as “the audio components 112 g”), one or more audioamplifiers 112 h (referred to hereinafter as “the amplifiers 112 h”),and power 112 i (e.g., one or more power supplies, power cables, powerreceptacles, batteries, induction coils, Power-over Ethernet (POE)interfaces, and/or other suitable sources of electric power). In someembodiments, the electronics 112 optionally include one or more othercomponents 112 j (e.g., one or more sensors, video displays,touchscreens, battery charging bases).

The processors 112 a can comprise clock-driven computing component(s)configured to process data, and the memory 112 b can comprise acomputer-readable medium (e.g., a tangible, non-transitorycomputer-readable medium, data storage loaded with one or more of thesoftware components 112 c) configured to store instructions forperforming various operations and/or functions. The processors 112 a areconfigured to execute the instructions stored on the memory 112 b toperform one or more of the operations. The operations can include, forexample, causing the playback device 110 a to retrieve audio data froman audio source (e.g., one or more of the computing devices 106 a-c(FIG. 1B)), and/or another one of the playback devices 110. In someembodiments, the operations further include causing the playback device110 a to send audio data to another one of the playback devices 110 aand/or another device (e.g., one of the NMDs 120). Certain embodimentsinclude operations causing the playback device 110 a to pair withanother of the one or more playback devices 110 to enable amulti-channel audio environment (e.g., a stereo pair, a bonded zone).

The processors 112 a can be further configured to perform operationscausing the playback device 110 a to synchronize playback of audiocontent with another of the one or more playback devices 110. As thoseof ordinary skill in the art will appreciate, during synchronousplayback of audio content on a plurality of playback devices, a listenerwill preferably be unable to perceive time-delay differences betweenplayback of the audio content by the playback device 110 a and the otherone or more other playback devices 110. Additional details regardingaudio playback synchronization among playback devices can be found, forexample, in U.S. Pat. No. 8,234,395, which was incorporated by referenceabove.

In some embodiments, the memory 112 b is further configured to storedata associated with the playback device 110 a, such as one or morezones and/or zone groups of which the playback device 110 a is a member,audio sources accessible to the playback device 110 a, and/or a playbackqueue that the playback device 110 a (and/or another of the one or moreplayback devices) can be associated with. The stored data can compriseone or more state variables that are periodically updated and used todescribe a state of the playback device 110 a. The memory 112 b can alsoinclude data associated with a state of one or more of the other devices(e.g., the playback devices 110, NMDs 120, control devices 130) of themedia playback system 100. In some aspects, for example, the state datais shared during predetermined intervals of time (e.g., every 5 seconds,every 10 seconds, every 60 seconds) among at least a portion of thedevices of the media playback system 100, so that one or more of thedevices have the most recent data associated with the media playbacksystem 100.

The network interface 112 d is configured to facilitate a transmissionof data between the playback device 110 a and one or more other deviceson a data network such as, for example, the links 103 and/or the network104 (FIG. 1B). The network interface 112 d is configured to transmit andreceive data corresponding to media content (e.g., audio content, videocontent, text, photographs) and other signals (e.g., non-transitorysignals) comprising digital packet data including an Internet Protocol(IP)-based source address and/or an IP-based destination address. Thenetwork interface 112 d can parse the digital packet data such that theelectronics 112 properly receives and processes the data destined forthe playback device 110 a.

In the illustrated embodiment of FIG. 1C, the network interface 112 dcomprises one or more wireless interfaces 112 e (referred to hereinafteras “the wireless interface 112 e”). The wireless interface 112 e (e.g.,a suitable interface comprising one or more antennae) can be configuredto wirelessly communicate with one or more other devices (e.g., one ormore of the other playback devices 110, NMDs 120, and/or control devices130) that are communicatively coupled to the network 104 (FIG. 1B) inaccordance with a suitable wireless communication protocol (e.g., WiFi,Bluetooth, LTE). In some embodiments, the network interface 112 doptionally includes a wired interface 112 f (e.g., an interface orreceptacle configured to receive a network cable such as an Ethernet, aUSB-A, USB-C, and/or Thunderbolt cable) configured to communicate over awired connection with other devices in accordance with a suitable wiredcommunication protocol. In certain embodiments, the network interface112 d includes the wired interface 112 f and excludes the wirelessinterface 112 e. In some embodiments, the electronics 112 excludes thenetwork interface 112 d altogether and transmits and receives mediacontent and/or other data via another communication path (e.g., theinput/output 111).

The audio components 112 g are configured to process and/or filter datacomprising media content received by the electronics 112 (e.g., via theinput/output 111 and/or the network interface 112 d) to produce outputaudio signals. In some embodiments, the audio processing components 112g comprise, for example, one or more digital-to-analog converters (DAC),audio preprocessing components, audio enhancement components, a digitalsignal processors (DSPs), and/or other suitable audio processingcomponents, modules, circuits, etc. In certain embodiments, one or moreof the audio processing components 112 g can comprise one or moresubcomponents of the processors 112 a. In some embodiments, theelectronics 112 omits the audio processing components 112 g. In someaspects, for example, the processors 112 a execute instructions storedon the memory 112 b to perform audio processing operations to producethe output audio signals.

The amplifiers 112 h are configured to receive and amplify the audiooutput signals produced by the audio processing components 112 g and/orthe processors 112 a. The amplifiers 112 h can comprise electronicdevices and/or components configured to amplify audio signals to levelssufficient for driving one or more of the transducers 114. In someembodiments, for example, the amplifiers 112 h include one or moreswitching or class-D power amplifiers. In other embodiments, however,the amplifiers include one or more other types of power amplifiers(e.g., linear gain power amplifiers, class-A amplifiers, class-Bamplifiers, class-AB amplifiers, class-C amplifiers, class-D amplifiers,class-E amplifiers, class-F amplifiers, class-G and/or class Hamplifiers, and/or another suitable type of power amplifier). In certainembodiments, the amplifiers 112 h comprise a suitable combination of twoor more of the foregoing types of power amplifiers. Moreover, in someembodiments, individual ones of the amplifiers 112 h correspond toindividual ones of the transducers 114. In other embodiments, however,the electronics 112 includes a single one of the amplifiers 112 hconfigured to output amplified audio signals to a plurality of thetransducers 114. In some other embodiments, the electronics 112 omitsthe amplifiers 112 h.

The transducers 114 (e.g., one or more speakers and/or speaker drivers)receive the amplified audio signals from the amplifier 112 h and renderor output the amplified audio signals as sound (e.g., audible soundwaves having a frequency between about 20 Hertz (Hz) and 20 kilohertz(kHz)). In some embodiments, the transducers 114 can comprise a singletransducer. In other embodiments, however, the transducers 114 comprisea plurality of audio transducers. In some embodiments, the transducers114 comprise more than one type of transducer. For example, thetransducers 114 can include one or more low frequency transducers (e.g.,subwoofers, woofers), mid-range frequency transducers (e.g., mid-rangetransducers, mid-woofers), and one or more high frequency transducers(e.g., one or more tweeters). As used herein, “low frequency” cangenerally refer to audible frequencies below about 500 Hz, “mid-rangefrequency” can generally refer to audible frequencies between about 500Hz and about 2 kHz, and “high frequency” can generally refer to audiblefrequencies above 2 kHz. In certain embodiments, however, one or more ofthe transducers 114 comprise transducers that do not adhere to theforegoing frequency ranges. For example, one of the transducers 114 maycomprise a mid-woofer transducer configured to output sound atfrequencies between about 200 Hz and about 5 kHz.

By way of illustration, SONOS, Inc. presently offers (or has offered)for sale certain playback devices including, for example, a “SONOS ONE,”“PLAY:1,” “PLAY:3,” “PLAY:5,” “PLAYBAR,” “PLAYBASE,” “CONNECT:AMP,”“CONNECT,” and “SUB.” Other suitable playback devices may additionallyor alternatively be used to implement the playback devices of exampleembodiments disclosed herein. Additionally, one of ordinary skilled inthe art will appreciate that a playback device is not limited to theexamples described herein or to SONOS product offerings. In someembodiments, for example, one or more playback devices 110 compriseswired or wireless headphones (e.g., over-the-ear headphones, on-earheadphones, in-ear earphones). In other embodiments, one or more of theplayback devices 110 comprise a docking station and/or an interfaceconfigured to interact with a docking station for personal mobile mediaplayback devices. In certain embodiments, a playback device may beintegral to another device or component such as a television, a lightingfixture, or some other device for indoor or outdoor use. In someembodiments, a playback device omits a user interface and/or one or moretransducers. For example, FIG. 1D is a block diagram of a playbackdevice 110 p comprising the input/output 111 and electronics 112 withoutthe user interface 113 or transducers 114.

FIG. 1E is a block diagram of a bonded playback device 110 q comprisingthe playback device 110 a (FIG. 1C) sonically bonded with the playbackdevice 110 i (e.g., a subwoofer) (FIG. 1A). In the illustratedembodiment, the playback devices 110 a and 110 i are separate ones ofthe playback devices 110 housed in separate enclosures. In someembodiments, however, the bonded playback device 110 q comprises asingle enclosure housing both the playback devices 110 a and 110 i. Thebonded playback device 110 q can be configured to process and reproducesound differently than an unbonded playback device (e.g., the playbackdevice 110 a of FIG. 1C) and/or paired or bonded playback devices (e.g.,the playback devices 110 l and 110 m of FIG. 1B). In some embodiments,for example, the playback device 110 a is full-range playback deviceconfigured to render low frequency, mid-range frequency, and highfrequency audio content, and the playback device 110 i is a subwooferconfigured to render low frequency audio content. In some aspects, theplayback device 110 a, when bonded with the first playback device, isconfigured to render only the mid-range and high frequency components ofa particular audio content, while the playback device 110 i renders thelow frequency component of the particular audio content. In someembodiments, the bonded playback device 110 q includes additionalplayback devices and/or another bonded playback device. Additionalplayback device embodiments are described in further detail below withrespect to FIGS. 2A-3D.

c. Suitable Network Microphone Devices (NMDs)

FIG. 1F is a block diagram of the NMD 120 a (FIGS. 1A and 1B). The NMD120 a includes one or more voice processing components 124 (hereinafter“the voice components 124”) and several components described withrespect to the playback device 110 a (FIG. 1C) including the processors112 a, the memory 112 b, and the microphones 115. The NMD 120 aoptionally comprises other components also included in the playbackdevice 110 a (FIG. 1C), such as the user interface 113 and/or thetransducers 114. In some embodiments, the NMD 120 a is configured as amedia playback device (e.g., one or more of the playback devices 110),and further includes, for example, one or more of the audio components112 g (FIG. 1C), the amplifiers 114, and/or other playback devicecomponents. In certain embodiments, the NMD 120 a comprises an Internetof Things (IoT) device such as, for example, a thermostat, alarm panel,fire and/or smoke detector, etc. In some embodiments, the NMD 120 acomprises the microphones 115, the voice processing 124, and only aportion of the components of the electronics 112 described above withrespect to FIG. 1B. In some aspects, for example, the NMD 120 a includesthe processor 112 a and the memory 112 b (FIG. 1B), while omitting oneor more other components of the electronics 112. In some embodiments,the NMD 120 a includes additional components (e.g., one or more sensors,cameras, thermometers, barometers, hygrometers).

In some embodiments, an NMD can be integrated into a playback device.FIG. 1G is a block diagram of a playback device 110 r comprising an NMD120 d. The playback device 110 r can comprise many or all of thecomponents of the playback device 110 a and further include themicrophones 115 and voice processing 124 (FIG. 1F). The playback device110 r optionally includes an integrated control device 130 c. Thecontrol device 130 c can comprise, for example, a user interface (e.g.,the user interface 113 of FIG. 1B) configured to receive user input(e.g., touch input, voice input) without a separate control device. Inother embodiments, however, the playback device 110 r receives commandsfrom another control device (e.g., the control device 130 a of FIG. 1B).Additional NMD embodiments are described in further detail below withrespect to FIGS. 3A-3F.

Referring again to FIG. 1F, the microphones 115 are configured toacquire, capture, and/or receive sound from an environment (e.g., theenvironment 101 of FIG. 1A) and/or a room in which the NMD 120 a ispositioned. The received sound can include, for example, vocalutterances, audio played back by the NMD 120 a and/or another playbackdevice, background voices, ambient sounds, etc. The microphones 115convert the received sound into electrical signals to produce microphonedata. The voice processing 124 receives and analyzes the microphone datato determine whether a voice input is present in the microphone data.The voice input can comprise, for example, an activation word followedby an utterance including a user request. As those of ordinary skill inthe art will appreciate, an activation word is a word or other audio cuethat signifying a user voice input. For instance, in querying theAMAZON® VAS, a user might speak the activation word “Alexa.” Otherexamples include “Ok, Google” for invoking the GOOGLE® VAS and “Hey,Siri” for invoking the APPLE® VAS.

After detecting the activation word, voice processing 124 monitors themicrophone data for an accompanying user request in the voice input. Theuser request may include, for example, a command to control athird-party device, such as a thermostat (e.g., NEST® thermostat), anillumination device (e.g., a PHILIPS HUE® lighting device), or a mediaplayback device (e.g., a Sonos® playback device). For example, a usermight speak the activation word “Alexa” followed by the utterance “setthe thermostat to 68 degrees” to set a temperature in a home (e.g., theenvironment 101 of FIG. 1A). The user might speak the same activationword followed by the utterance “turn on the living room” to turn onillumination devices in a living room area of the home. The user maysimilarly speak an activation word followed by a request to play aparticular song, an album, or a playlist of music on a playback devicein the home. Additional description regarding receiving and processingvoice input data can be found in further detail below with respect toFIGS. 3A-3F.

d. Suitable Control Devices

FIG. 1H is a partially schematic diagram of the control device 130 a(FIGS. 1A and 1B). As used herein, the term “control device” can be usedinterchangeably with “controller” or “control system.” Among otherfeatures, the control device 130 a is configured to receive user inputrelated to the media playback system 100 and, in response, cause one ormore devices in the media playback system 100 to perform an action(s) oroperation(s) corresponding to the user input. In the illustratedembodiment, the control device 130 a comprises a smartphone (e.g., aniPhone™, an Android phone) on which media playback system controllerapplication software is installed. In some embodiments, the controldevice 130 a comprises, for example, a tablet (e.g., an iPad™), acomputer (e.g., a laptop computer, a desktop computer), and/or anothersuitable device (e.g., a television, an automobile audio head unit, anIoT device). In certain embodiments, the control device 130 a comprisesa dedicated controller for the media playback system 100. In otherembodiments, as described above with respect to FIG. 1G, the controldevice 130 a is integrated into another device in the media playbacksystem 100 (e.g., one more of the playback devices 110, NMDs 120, and/orother suitable devices configured to communicate over a network).

The control device 130 a includes electronics 132, a user interface 133,one or more speakers 134, and one or more microphones 135. Theelectronics 132 comprise one or more processors 132 a (referred tohereinafter as “the processors 132 a”), a memory 132 b, softwarecomponents 132 c, and a network interface 132 d. The processor 132 a canbe configured to perform functions relevant to facilitating user access,control, and configuration of the media playback system 100. The memory132 b can comprise data storage that can be loaded with one or more ofthe software components executable by the processor 302 to perform thosefunctions. The software components 132 c can comprise applicationsand/or other executable software configured to facilitate control of themedia playback system 100. The memory 112 b can be configured to store,for example, the software components 132 c, media playback systemcontroller application software, and/or other data associated with themedia playback system 100 and the user.

The network interface 132 d is configured to facilitate networkcommunications between the control device 130 a and one or more otherdevices in the media playback system 100, and/or one or more remotedevices. In some embodiments, the network interface 132 is configured tooperate according to one or more suitable communication industrystandards (e.g., infrared, radio, wired standards including IEEE 802.3,wireless standards including IEEE 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, 802.15, 4G, LTE). The network interface 132 d can beconfigured, for example, to transmit data to and/or receive data fromthe playback devices 110, the NMDs 120, other ones of the controldevices 130, one of the computing devices 106 of FIG. 1B, devicescomprising one or more other media playback systems, etc. Thetransmitted and/or received data can include, for example, playbackdevice control commands, state variables, playback zone and/or zonegroup configurations. For instance, based on user input received at theuser interface 133, the network interface 132 d can transmit a playbackdevice control command (e.g., volume control, audio playback control,audio content selection) from the control device 304 to one or more ofthe playback devices 100. The network interface 132 d can also transmitand/or receive configuration changes such as, for example,adding/removing one or more playback devices 100 to/from a zone,adding/removing one or more zones to/from a zone group, forming a bondedor consolidated player, separating one or more playback devices from abonded or consolidated player, among others. Additional description ofzones and groups can be found below with respect to FIGS. 1 -I through1M.

The user interface 133 is configured to receive user input and canfacilitate control of the media playback system 100. The user interface133 includes media content art 133 a (e.g., album art, lyrics, videos),a playback status indicator 133 b (e.g., an elapsed and/or remainingtime indicator), media content information region 133 c, a playbackcontrol region 133 d, and a zone indicator 133 e. The media contentinformation region 133 c can include a display of relevant information(e.g., title, artist, album, genre, release year) about media contentcurrently playing and/or media content in a queue or playlist. Theplayback control region 133 d can include selectable (e.g., via touchinput and/or via a cursor or another suitable selector) icons to causeone or more playback devices in a selected playback zone or zone groupto perform playback actions such as, for example, play or pause, fastforward, rewind, skip to next, skip to previous, enter/exit shufflemode, enter/exit repeat mode, enter/exit cross fade mode, etc. Theplayback control region 133 d may also include selectable icons tomodify equalization settings, playback volume, and/or other suitableplayback actions. In the illustrated embodiment, the user interface 133comprises a display presented on a touch screen interface of asmartphone (e.g., an iPhone™, an Android phone). In some embodiments,however, user interfaces of varying formats, styles, and interactivesequences may alternatively be implemented on one or more networkdevices to provide comparable control access to a media playback system.

The one or more speakers 134 (e.g., one or more transducers) can beconfigured to output sound to the user of the control device 130 a. Insome embodiments, the one or more speakers comprise individualtransducers configured to correspondingly output low frequencies,mid-range frequencies, and/or high frequencies. In some aspects, forexample, the control device 130 a is configured as a playback device(e.g., one of the playback devices 110). Similarly, in some embodimentsthe control device 130 a is configured as an NMD (e.g., one of the NMDs120), receiving voice commands and other sounds via the one or moremicrophones 135.

The one or more microphones 135 can comprise, for example, one or morecondenser microphones, electret condenser microphones, dynamicmicrophones, and/or other suitable types of microphones or transducers.In some embodiments, two or more of the microphones 135 are arranged tocapture location information of an audio source (e.g., voice, audiblesound) and/or configured to facilitate filtering of background noise.Moreover, in certain embodiments, the control device 130 a is configuredto operate as playback device and an NMD. In other embodiments, however,the control device 130 a omits the one or more speakers 134 and/or theone or more microphones 135. For instance, the control device 130 a maycomprise a device (e.g., a thermostat, an IoT device, a network device)comprising a portion of the electronics 132 and the user interface 133(e.g., a touch screen) without any speakers or microphones.

e. Suitable Playback Device Configurations

FIGS. 1 -I through 1M show example configurations of playback devices inzones and zone groups. Referring first to FIG. 1M, in one example, asingle playback device may belong to a zone. For example, the playbackdevice 110 g in the second bedroom 101 c (FIG. 1A) may belong to Zone C.In some implementations described below, multiple playback devices maybe “bonded” to form a “bonded pair” which together form a single zone.For example, the playback device 110 l (e.g., a left playback device)can be bonded to the playback device 110 m (e.g., a right playbackdevice) to form Zone B. Bonded playback devices may have differentplayback responsibilities (e.g., channel responsibilities). In anotherimplementation described below, multiple playback devices may be mergedto form a single zone. For example, the playback device 110 h (e.g., afront playback device) may be merged with the playback device 110 i(e.g., a subwoofer), and the playback devices 110 j and 110 k (e.g.,left and right surround speakers, respectively) to form a single Zone D.In another example, the playback devices 110 g and 110 h can be mergedto form a merged group or a zone group 108 b. The merged playbackdevices 110 g and 110 h may not be specifically assigned differentplayback responsibilities. That is, the merged playback devices 110 hand 110 i may, aside from playing audio content in synchrony, each playaudio content as they would if they were not merged.

Each zone in the media playback system 100 may be provided for controlas a single user interface (UI) entity. For example, Zone A may beprovided as a single entity named Master Bathroom. Zone B may beprovided as a single entity named Master Bedroom. Zone C may be providedas a single entity named Second Bedroom.

Playback devices that are bonded may have different playbackresponsibilities, such as responsibilities for certain audio channels.For example, as shown in FIG. 1 -I, the playback devices 110 l and 110 mmay be bonded so as to produce or enhance a stereo effect of audiocontent. In this example, the playback device 110 l may be configured toplay a left channel audio component, while the playback device 110 k maybe configured to play a right channel audio component. In someimplementations, such stereo bonding may be referred to as “pairing.”

Additionally, bonded playback devices may have additional and/ordifferent respective speaker drivers. As shown in FIG. 1J, the playbackdevice 110 h named Front may be bonded with the playback device 110 inamed SUB. The Front device 110 h can be configured to render a range ofmid to high frequencies and the SUB device 110 i can be configuredrender low frequencies. When unbonded, however, the Front device 110 hcan be configured render a full range of frequencies. As anotherexample, FIG. 1K shows the Front and SUB devices 110 h and 110 i furtherbonded with Left and Right playback devices 110 j and 110 k,respectively. In some implementations, the Right and Left devices 110 jand 102 k can be configured to form surround or “satellite” channels ofa home theater system. The bonded playback devices 110 h, 110 i, 110 j,and 110 k may form a single Zone D (FIG. 1M).

Playback devices that are merged may not have assigned playbackresponsibilities, and may each render the full range of audio contentthe respective playback device is capable of. Nevertheless, mergeddevices may be represented as a single UI entity (i.e., a zone, asdiscussed above). For instance, the playback devices 110 a and 110 n ofthe master bathroom have the single UI entity of Zone A. In oneembodiment, the playback devices 110 a and 110 n may each output thefull range of audio content each respective playback devices 110 a and110 n are capable of, in synchrony.

In some embodiments, an NMD is bonded or merged with another device soas to form a zone. For example, the NMD 120 b may be bonded with theplayback device 110 e, which together form Zone F, named Living Room. Inother embodiments, a stand-alone network microphone device may be in azone by itself. In other embodiments, however, a stand-alone networkmicrophone device may not be associated with a zone. Additional detailsregarding associating network microphone devices and playback devices asdesignated or default devices may be found, for example, in previouslyreferenced U.S. patent application Ser. No. 15/438,749.

Zones of individual, bonded, and/or merged devices may be grouped toform a zone group. For example, referring to FIG. 1M, Zone A may begrouped with Zone B to form a zone group 108 a that includes the twozones. Similarly, Zone G may be grouped with Zone H to form the zonegroup 108 b. As another example, Zone A may be grouped with one or moreother Zones C-I. The Zones A-I may be grouped and ungrouped in numerousways. For example, three, four, five, or more (e.g., all) of the ZonesA-I may be grouped. When grouped, the zones of individual and/or bondedplayback devices may play back audio in synchrony with one another, asdescribed in previously referenced U.S. Pat. No. 8,234,395. Playbackdevices may be dynamically grouped and ungrouped to form new ordifferent groups that synchronously play back audio content.

In various implementations, the zones in an environment may be thedefault name of a zone within the group or a combination of the names ofthe zones within a zone group. For example, Zone Group 108 b can have beassigned a name such as “Dining+Kitchen”, as shown in FIG. 1M. In someembodiments, a zone group may be given a unique name selected by a user.

Certain data may be stored in a memory of a playback device (e.g., thememory 112 c of FIG. 1C) as one or more state variables that areperiodically updated and used to describe the state of a playback zone,the playback device(s), and/or a zone group associated therewith. Thememory may also include the data associated with the state of the otherdevices of the media system, and shared from time to time among thedevices so that one or more of the devices have the most recent dataassociated with the system.

In some embodiments, the memory may store instances of various variabletypes associated with the states. Variables instances may be stored withidentifiers (e.g., tags) corresponding to type. For example, certainidentifiers may be a first type “a1” to identify playback device(s) of azone, a second type “b1” to identify playback device(s) that may bebonded in the zone, and a third type “c1” to identify a zone group towhich the zone may belong. As a related example, identifiers associatedwith the second bedroom 101 c may indicate that the playback device isthe only playback device of the Zone C and not in a zone group.Identifiers associated with the Den may indicate that the Den is notgrouped with other zones but includes bonded playback devices 110 h-110k. Identifiers associated with the Dining Room may indicate that theDining Room is part of the Dining+Kitchen zone group 108 b and thatdevices 110 b and 110 d are grouped (FIG. 1L). Identifiers associatedwith the Kitchen may indicate the same or similar information by virtueof the Kitchen being part of the Dining+Kitchen zone group 108 b. Otherexample zone variables and identifiers are described below.

In yet another example, the media playback system 100 may variables oridentifiers representing other associations of zones and zone groups,such as identifiers associated with Areas, as shown in FIG. 1M. An areamay involve a cluster of zone groups and/or zones not within a zonegroup. For instance, FIG. 1M shows an Upper Area 109 a including ZonesA-D, and a Lower Area 109 b including Zones E-I. In one aspect, an Areamay be used to invoke a cluster of zone groups and/or zones that shareone or more zones and/or zone groups of another cluster. In anotheraspect, this differs from a zone group, which does not share a zone withanother zone group. Further examples of techniques for implementingAreas may be found, for example, in U.S. application Ser. No. 15/682,506filed Aug. 21, 2017 and titled “Room Association Based on Name,” andU.S. Pat. No. 8,483,853 filed Sep. 11, 2007, and titled “Controlling andmanipulating groupings in a multi-zone media system.” Each of theseapplications is incorporated herein by reference in its entirety. Insome embodiments, the media playback system 100 may not implement Areas,in which case the system may not store variables associated with Areas.

III. Example Systems and Devices

FIG. 2A is a front isometric view of a playback device 210 configured inaccordance with aspects of the disclosed technology. FIG. 2B is a frontisometric view of the playback device 210 without a grille 216 e. FIG.2C is an exploded view of the playback device 210. Referring to FIGS.2A-2C together, the playback device 210 comprises a housing 216 thatincludes an upper portion 216 a, a right or first side portion 216 b, alower portion 216 c, a left or second side portion 216 d, the grille 216e, and a rear portion 216 f A plurality of fasteners 216 g (e.g., one ormore screws, rivets, clips) attaches a frame 216 h to the housing 216. Acavity 216 j (FIG. 2C) in the housing 216 is configured to receive theframe 216 h and electronics 212. The frame 216 h is configured to carrya plurality of transducers 214 (identified individually in FIG. 2B astransducers 214 a-f). The electronics 212 (e.g., the electronics 112 ofFIG. 1C) is configured to receive audio content from an audio source andsend electrical signals corresponding to the audio content to thetransducers 214 for playback.

The transducers 214 are configured to receive the electrical signalsfrom the electronics 112, and further configured to convert the receivedelectrical signals into audible sound during playback. For instance, thetransducers 214 a-c (e.g., tweeters) can be configured to output highfrequency sound (e.g., sound waves having a frequency greater than about2 kHz). The transducers 214 d-f (e.g., mid-woofers, woofers, midrangespeakers) can be configured output sound at frequencies lower than thetransducers 214 a-c (e.g., sound waves having a frequency lower thanabout 2 kHz). In some embodiments, the playback device 210 includes anumber of transducers different than those illustrated in FIGS. 2A-2C.For example, as described in further detail below with respect to FIGS.3A-3C, the playback device 210 can include fewer than six transducers(e.g., one, two, three). In other embodiments, however, the playbackdevice 210 includes more than six transducers (e.g., nine, ten).Moreover, in some embodiments, all or a portion of the transducers 214are configured to operate as a phased array to desirably adjust (e.g.,narrow or widen) a radiation pattern of the transducers 214, therebyaltering a user's perception of the sound emitted from the playbackdevice 210.

In the illustrated embodiment of FIGS. 2A-2C, a filter 216 i is axiallyaligned with the transducer 214 b. The filter 216 i can be configured todesirably attenuate a predetermined range of frequencies that thetransducer 214 b outputs to improve sound quality and a perceived soundstage output collectively by the transducers 214. In some embodiments,however, the playback device 210 omits the filter 216 i. In otherembodiments, the playback device 210 includes one or more additionalfilters aligned with the transducers 214 b and/or at least another ofthe transducers 214.

FIGS. 3A and 3B are front and right isometric side views, respectively,of an NMD 320 configured in accordance with embodiments of the disclosedtechnology. FIG. 3C is an exploded view of the NMD 320. FIG. 3D is anenlarged view of a portion of FIG. 3B including a user interface 313 ofthe NMD 320. Referring first to FIGS. 3A-3C, the NMD 320 includes ahousing 316 comprising an upper portion 316 a, a lower portion 316 b andan intermediate portion 316 c (e.g., a grille). A plurality of ports,holes or apertures 316 d in the upper portion 316 a allow sound to passthrough to one or more microphones 315 (FIG. 3C) positioned within thehousing 316. The one or more microphones 315 are configured to receivedsound via the apertures 316 d and produce electrical signals based onthe received sound. In the illustrated embodiment, a frame 316 e (FIG.3C) of the housing 316 surrounds cavities 316 f and 316 g configured tohouse, respectively, a first transducer 314 a (e.g., a tweeter) and asecond transducer 314 b (e.g., a mid-woofer, a midrange speaker, awoofer). In other embodiments, however, the NMD 320 includes a singletransducer, or more than two (e.g., two, five, six) transducers. Incertain embodiments, the NMD 320 omits the transducers 314 a and 314 baltogether.

Electronics 312 (FIG. 3C) includes components configured to drive thetransducers 314 a and 314 b, and further configured to analyze audiodata corresponding to the electrical signals produced by the one or moremicrophones 315. In some embodiments, for example, the electronics 312comprises many or all of the components of the electronics 112 describedabove with respect to FIG. 1C. In certain embodiments, the electronics312 includes components described above with respect to FIG. 1F such as,for example, the one or more processors 112 a, the memory 112 b, thesoftware components 112 c, the network interface 112 d, etc. In someembodiments, the electronics 312 includes additional suitable components(e.g., proximity or other sensors).

Referring to FIG. 3D, the user interface 313 includes a plurality ofcontrol surfaces (e.g., buttons, knobs, capacitive surfaces) including afirst control surface 313 a (e.g., a previous control), a second controlsurface 313 b (e.g., a next control), and a third control surface 313 c(e.g., a play and/or pause control). A fourth control surface 313 d isconfigured to receive touch input corresponding to activation anddeactivation of the one or microphones 315. A first indicator 313 e(e.g., one or more light emitting diodes (LEDs) or another suitableilluminator) can be configured to illuminate only when the one or moremicrophones 315 are activated. A second indicator 313 f (e.g., one ormore LEDs) can be configured to remain solid during normal operation andto blink or otherwise change from solid to indicate a detection of voiceactivity. In some embodiments, the user interface 313 includesadditional or fewer control surfaces and illuminators. In oneembodiment, for example, the user interface 313 includes the firstindicator 313 e, omitting the second indicator 313 f Moreover, incertain embodiments, the NMD 320 comprises a playback device and acontrol device, and the user interface 313 comprises the user interfaceof the control device.

Referring to FIGS. 3A-3D together, the NMD 320 is configured to receivevoice commands from one or more adjacent users via the one or moremicrophones 315. As described above with respect to FIG. 1B, the one ormore microphones 315 can acquire, capture, or record sound in a vicinity(e.g., a region within 10 m or less of the NMD 320) and transmitelectrical signals corresponding to the recorded sound to theelectronics 312. The electronics 312 can process the electrical signalsand can analyze the resulting audio data to determine a presence of oneor more voice commands (e.g., one or more activation words). In someembodiments, for example, after detection of one or more suitable voicecommands, the NMD 320 is configured to transmit a portion of therecorded audio data to another device and/or a remote server (e.g., oneor more of the computing devices 106 of FIG. 1B) for further analysis.The remote server can analyze the audio data, determine an appropriateaction based on the voice command, and transmit a message to the NMD 320to perform the appropriate action. For instance, a user may speak“Sonos, play Michael Jackson.” The NMD 320 can, via the one or moremicrophones 315, record the user's voice utterance, determine thepresence of a voice command, and transmit the audio data having thevoice command to a remote server (e.g., one or more of the remotecomputing devices 106 of FIG. 1B, one or more servers of a VAS and/oranother suitable service). The remote server can analyze the audio dataand determine an action corresponding to the command. The remote servercan then transmit a command to the NMD 320 to perform the determinedaction (e.g., play back audio content related to Michael Jackson). TheNMD 320 can receive the command and play back the audio content relatedto Michael Jackson from a media content source. As described above withrespect to FIG. 1B, suitable content sources can include a device orstorage communicatively coupled to the NMD 320 via a LAN (e.g., thenetwork 104 of FIG. 1B), a remote server (e.g., one or more of theremote computing devices 106 of FIG. 1B), etc. In certain embodiments,however, the NMD 320 determines and/or performs one or more actionscorresponding to the one or more voice commands without intervention orinvolvement of an external device, computer, or server.

FIG. 3E is a functional block diagram showing additional features of theNMD 320 in accordance with aspects of the disclosure. The NMD 320includes components configured to facilitate voice command captureincluding voice activity detector component(s) 312 k, beam formercomponents 312 l, acoustic echo cancellation (AEC) and/or self-soundsuppression components 312 m, activation word detector components 312 n,and voice/speech conversion components 312 o (e.g., voice-to-text andtext-to-voice). In the illustrated embodiment of FIG. 3E, the foregoingcomponents 312 k-312 o are shown as separate components. In someembodiments, however, one or more of the components 312 k-312 o aresubcomponents of the processors 112 a.

The beamforming and self-sound suppression components 312 l and 312 mare configured to detect an audio signal and determine aspects of voiceinput represented in the detected audio signal, such as the direction,amplitude, frequency spectrum, etc. The voice activity detector activitycomponents 312 k are operably coupled with the beamforming and AECcomponents 312 l and 312 m and are configured to determine a directionand/or directions from which voice activity is likely to have occurredin the detected audio signal. Potential speech directions can beidentified by monitoring metrics which distinguish speech from othersounds. Such metrics can include, for example, energy within the speechband relative to background noise and entropy within the speech band,which is measure of spectral structure. As those of ordinary skill inthe art will appreciate, speech typically has a lower entropy than mostcommon background noise. The activation word detector components 312 nare configured to monitor and analyze received audio to determine if anyactivation words (e.g., wake words) are present in the received audio.The activation word detector components 312 n may analyze the receivedaudio using an activation word detection algorithm. If the activationword detector 312 n detects an activation word, the NMD 320 may processvoice input contained in the received audio. Example activation worddetection algorithms accept audio as input and provide an indication ofwhether an activation word is present in the audio. Many first- andthird-party activation word detection algorithms are known andcommercially available. For instance, operators of a voice service maymake their algorithm available for use in third-party devices.Alternatively, an algorithm may be trained to detect certain activationwords. In some embodiments, the activation word detector 312 n runsmultiple activation word detection algorithms on the received audiosimultaneously (or substantially simultaneously). As noted above,different voice services (e.g. AMAZON's ALEXA®, APPLE's SIRI®, orMICROSOFT's CORTANA®) can each use a different activation word forinvoking their respective voice service. To support multiple services,the activation word detector 312 n may run the received audio throughthe activation word detection algorithm for each supported voice servicein parallel.

The speech/text conversion components 312 o may facilitate processing byconverting speech in the voice input to text. In some embodiments, theelectronics 312 can include voice recognition software that is trainedto a particular user or a particular set of users associated with ahousehold. Such voice recognition software may implementvoice-processing algorithms that are tuned to specific voice profile(s).Tuning to specific voice profiles may require less computationallyintensive algorithms than traditional voice activity services, whichtypically sample from a broad base of users and diverse requests thatare not targeted to media playback systems.

FIG. 3F is a schematic diagram of an example voice input 328 captured bythe NMD 320 in accordance with aspects of the disclosure. The voiceinput 328 can include an activation word portion 328 a and a voiceutterance portion 328 b. In some embodiments, the activation word 557 acan be a known activation word, such as “Alexa,” which is associatedwith AMAZON's ALEXA®. In other embodiments, however, the voice input 328may not include an activation word. In some embodiments, a networkmicrophone device may output an audible and/or visible response upondetection of the activation word portion 328 a. In addition oralternately, an NMB may output an audible and/or visible response afterprocessing a voice input and/or a series of voice inputs.

The voice utterance portion 328 b may include, for example, one or morespoken commands (identified individually as a first command 328 c and asecond command 328 e) and one or more spoken keywords (identifiedindividually as a first keyword 328 d and a second keyword 328 f). Inone example, the first command 328 c can be a command to play music,such as a specific song, album, playlist, etc. In this example, thekeywords may be one or words identifying one or more zones in which themusic is to be played, such as the Living Room and the Dining Room shownin FIG. 1A. In some examples, the voice utterance portion 328 b caninclude other information, such as detected pauses (e.g., periods ofnon-speech) between words spoken by a user, as shown in FIG. 3F. Thepauses may demarcate the locations of separate commands, keywords, orother information spoke by the user within the voice utterance portion328 b.

In some embodiments, the media playback system 100 is configured totemporarily reduce the volume of audio content that it is playing whiledetecting the activation word portion 557 a. The media playback system100 may restore the volume after processing the voice input 328, asshown in FIG. 3F. Such a process can be referred to as ducking, examplesof which are disclosed in U.S. patent application Ser. No. 15/438,749,incorporated by reference herein in its entirety.

IV. Playback Characteristics Based on Listener Location

FIG. 4 shows a representation of a playback environment 401 occupied bya listener 403. The playback environment 401 in this example is a livingroom 110 f (FIG. 1A). Other examples may be applied to any otherenvironment in which playback devices are installed. For clarity, theplayback environment 401 is shown as being substantially rectangular,but it will be appreciated that other playback environments may havedifferent sized and/or shapes, and may contain any number of additionalfeatures, for example furniture and/or doorways, which may affect theacoustic properties of the playback environment. Other examples ofplayback environments include interiors of vehicles and/or commercialsettings, as discussed above. A playback environment may correspond to aplayback zone in a playback system such as that described above withreference to FIG. 1A, though in other examples a playback environmentmay only be part of a playback zone, or alternatively may incorporatemultiple playback zones.

The playback environment 401 contains a playback device 410 configuredto perform audio reproduction from a media source. The playback deviceis substantially as described above with reference to FIG. 1C butincludes microphones. As shown in FIG. 5 , the playback device 410includes input/output 411, electronics 412, a user interface 413, one ormore transducers 414, and one or more microphones 415. In this example,the transducers 414 include a tweeter 414 a that is configured togenerate sound signals having a relatively high frequency (for examplebetween about 2 kHz and about 22 kHz) and a mid-woofer 414 b that isconfigured to generate low to mid-frequency acoustic waves (for example,acoustic waves having a frequency of between about 40 Hz and about 2kHz). Other examples of playback devices configured to perform themethods described hereafter may include more or fewer transducers, andmay include other types of transducer, for example a subwoofer, or mayomit any of the above-mentioned types of transducer. Furthermore, themethods described hereafter may be performed by a bonded playback deviceas described above with reference to FIG. 1E.

The electronics 412 of the playback device 410 in this example includeequivalent components to the electronics 112 of the playback device 110described above with reference to FIG. 1C, and additionally includeaudio processing components for processing sound signals received by theone or more microphones 415. It is noted that the methods describedhereafter may be performed by an NMD incorporating a playback device, orby a playback device incorporating an NMD. For example, the NMD 320(FIG. 3C), which includes one or more transducers 314 that may be usedfor audio reproduction, may be configured to perform the methodsdescribed hereafter.

The playback device 410 is arranged to select a characteristic of audioreproduction based on a location of a person, for example listener 403,with respect to the playback device 403. Examples of characteristicsthat may be selected include a volume of audio reproduction orequalization levels for audio reproduction. Further examples ofcharacteristics of audio reproduction will be described in detailhereafter. As will be apparent from these examples, selecting acharacteristic of audio reproduction based on a location of a listenermay result in an improved or enhanced listening experience for thelistener, and/or further additional or improved aspects of userexperience for the listener.

FIG. 6 is a flow diagram of a method 600 in which the playback device410 selects a characteristic of audio reproduction based on a locationof a person relative to the playback device 410. The playback device 410transmits, at S610, a first sound signal containing a predeterminedwaveform. In this example, the first sound signal is an up-chirp whichis a sound signal having a frequency that increases with time in apredetermined manner. Other examples of sound signals that may betransmitted include a down-chirp (a sound signal having a frequency thatdecreases with time in a predetermined manner), constant-frequencypulse, or Frequency-Modulated Continuous Wave (FMCW) signals. In theexample of FIG. 4 , a first sound signal 405 is transmitted by theplayback device 410 into the playback environment 401. The first soundsignal 405 is represented in FIG. 4 as a ray. It will be appreciatedthat a ray is an idealized model of a sound wave, and corresponds to adirection of energy flow that is locally perpendicular to wave fronts ofthe sound wave.

In the present example, the first sound signal 405 is an ultrasonicsound signal generated by the tweeter 414 a. An ultrasonic sound signalhas a frequency that is higher than the highest frequency of sound thatis audible to an average person, for example higher than 20 kHz. It isnoted that the highest audible sound varies significantly betweenpeople, so for the purpose of the present disclosure, an ultrasonicsound signal may be considered to have a frequency that remains above 20kHz for the duration of the sound signal. As mentioned above, thetweeter 414 a is configured to generate sound signals having a frequencyof between about 2 kHz and 22 kHz, and therefore is configured togenerate ultrasonic sound signals with a frequency of between about 20kHz and 22 kHz. Transducers such as tweeters may be manufactured to beable to generate sound signals outside the audible range of humanhearing in order to reduce detrimental effects associated with roll-offnear the extremes of the audible hearing range. In the present example,the first sound signal 405 is an ultrasonic chirp with a duration ofabout 10 ms, with a frequency that rises in a predetermined mannerwithin a range of between about 20 kHz and 22 kHz. In other examples,however, the tweeter 414 is configured to generate sound signals havingfrequencies greater than 22 kHz (e.g., sound signals having frequencies25 kHz and higher).

Under standard temperature and pressure (STP) conditions, ultrasoundwaves in the frequency ranges discussed above typically have wavelengthsless than about 2 cm. Due to the relatively short wavelength ofultrasonic sound waves relative to the size of many transducers(including tweeter 414 a) and/or apertures through which sound signalsare emitted, angular dispersion or angular spread of ultrasonic soundsignals generated by such transducers is limited to a relatively narrowangle (e.g., less than about 10 degrees from normal, less than about 5degrees from normal, or less than about 1 degree from normal). As aresult, ultrasonic sound signals may be transmitted as a relativelynarrow beam, in contrast to lower frequency sound signals for whichdiffractive effects cause wide-angle dispersion. This makes ultrasonicsound waves (as well as high-frequency audible sound waves, for exampleaudible sound waves with a frequency greater than about 8 kHz, about 10kHz, about 12 kHz, about 14 kHz, or about 18 kHz) suitable for use inthe present method, for the reasons described hereafter.

Returning to the method of FIG. 6 , the playback device 410 receives, atS620, a second sound signal using the one or more microphones 415. Thesecond sound signal contains at least one reflection of the first soundsignal. In the example of FIG. 4 , three reflections 407 a, 407 b, and407 c (collectively referred to as reflections 407) of the first soundsignal 405 are shown, each reflection represented by a ray. The firstreflected ray 407 a corresponds to a reflection of the first soundsignal 403 in which the first sound signal 403 is normally incident onpart of the listener 403, and accordingly is reflected directly back tothe playback device 410. The second reflected ray 407 b corresponds to areflection of the first sound signal 403 in which the first sound signal403 is obliquely incident on part of the listener 403, and is reflectedindirectly back to the playback device 410, having first been reflectedoff the left hand wall of the playback environment 401. The thirdreflected ray 407 c also corresponds to a reflection of the first soundsignal 403 in which the first sound signal 403 is reflected indirectlyback to the playback device 410, in this case having first beenreflected off three walls of the playback environment 401. In reality,the propagation of sound waves in the playback environment 410 will becomplicated by, for example, diffractive effects, and many otherreflections will be present in a reverberant environment such as theplayback environment 410. The reflected rays 407 are included forillustrative purposes only.

Although the number of reflections of the sound signal 405 is likely tobe large, the relatively narrow beam angle of the first sound signal 405reduces the likelihood that direct reflections of the first sound signal405 from the back wall or side walls (shown in FIG. 4 as the left,right, and lower walls) are present because the beam may be blockedbefore reaching them. In the specific arrangement shown in FIG. 4 , thefirst reflected ray to reach the playback device 410 is the ray 407 areflected directly from the listener 403. In other arrangements, raysreflected directly or indirectly from other objects of features within aplayback environment may reach a playback device before any ray directlyreflected from a person. In some arrangements, for example where alistener is not located within a path of a beam transmitted by aplayback device, there may not be any significant direct reflection fromthe listener.

The second sound signal is processed, at S630, to determine a locationof a person relative to the playback device 410. In the presentembodiment, audio processing components of the electronics 412 of theplayback device 410 process the second sound signal. However, playbackdevices in other embodiments may alternatively be arranged to send datato a remote computer system for remote processing. In some of theseexamples, a playback device is arranged to transmit, using a networkinterface, data indicative of a second sound signal to a computingsystem for remote processing. The computing system is arranged toprocess the second sound signal and transmit, using the networkinterface, data indicative of the location of the person relative to theplayback device. The playback device is arranged to receive the dataindicative of the location of the person, thereby to determine thelocation of the person relative to the playback device.

A location of a person may be determined in a variety of ways. In someexamples, a feature within a received second sound signal is identifiedas being a reflection of a transmitted signal by a person. An example ofa feature within a received sound signal is a reflection of all or partof a predetermined waveform, or a peak in amplitude in the receivedsignal. A reflection of a transmitted signal by a person may be director indirect, as discussed above with reference to FIG. 4 . If a featureis identified as being a direct reflection of a transmitted signal by aperson, a distance from the playback device to the person can bedetermined using echo-location or range-finding techniques, whereby thedistance is determined using the equation d=ct/2, where d is thedistance from the playback device to the determined location of theperson, t is the time between transmission of a feature within thetransmitted signal and receipt of a corresponding feature within thereceived signal, and c is the speed of sound in air (approximately 340m/s under STP conditions). Identifying a feature as a direct reflectionby a person may include comparing a received sound signal with abaseline signal received when no person is present in the playbackenvironment, and identifying from the comparison one or more additionalfeatures in the sound signal received when a person is present in theplayback zone. The first such feature to appear in the received signalmay be determined to be a direct reflection by a person. For exampleswhere echo-location techniques are employed to determine a location of aperson, sound signals containing a predetermined FMCW (for example, achirp) allow for improved distance resolution, as cross-correlation maybe used to match the reflected signal with a reference signal containingthe FMCW with a given temporal offset.

The baseline signal may be a signal transmitted at a time when no one islikely to be in the room, such as a time between midnight and 6 am,between lam and 5 am, or between 2 am and 4 am, for example at about 3am, about 4 am, or about 5 am. The comparison may identify differencesfrom the baseline signal, e.g. by subtracting the baseline signal fromthe received signal. Using a baseline signal can remove the effects ofboth the self-response of the playbacks device and the response fromfurniture and other items in the environment. In some examples, thebaseline signal may be transmitted and measured periodically, forexample once a day, once a week, or once a month to identify potentialchanges such as changes in the position of furniture and/or other itemsin the environment. The baseline signal may be established from a singlemeasurement of from a plurality of measurements, e.g. by taking anaverage.

FIG. 7 shows an example of 1250 data samples generated by passing asound signal received by a playback device through a multi-stagenoise-shaping (MASH) modulator. Each of the discrete peaks in the datacorresponds to an amplitude peak in the received second sound signal. Inthis example, the first peak 702 corresponds to a self-response of theplayback device caused by a transducer of the playback devicetransmitting a first sound signal. The second peak 704 corresponds to adirect reflection of the first sound signal by a person (similar to thereflection 407 a of FIG. 4 ). The third peak 706 corresponds to anindirect reflection of the first sound signal by a person (similar tothe reflection 407 b of FIG. 4 ).

In some examples, processing a second sound signal to determine alocation of a person relative to a playback device includes disregardinga portion of the second sound signal corresponding to a self-response ofthe playback device. A playback device may have a significantself-response for at least a part of the frequency range generated bythe playback device. A self-response may be, for example, a resonance ofall or part of the playback device induced by a transducer of theplayback device generating a sound signal, and/or internal reflectionsof a generated sound signal within the playback device. In someexamples, the self-response may be the most prominent feature of a soundsignal received by a microphone of the playback device. This is incontrast with devices solely or primarily designed to performecho-location, for example sonar transceivers, which are designed tominimize self-response. Disregarding a portion of the received secondsound signal corresponding to a self-response of the playback device mayimprove the accuracy with which a location of a person is determined,especially where determining a location of a person involves determininga correspondence between the received second sound signal and storedsignal data, examples of which will be described in detail hereafter.Disregarding a portion of the received sound signal may includedisregarding a portion of the signal having a predetermined duration.The predetermined duration for a given playback device will depend onthe self-response of the given playback device, and may be different fordifferent models of playback device. In some examples, the microphone isactivated only after the portion of the second sound signal is expectedto be received, resulting in the portion being disregardedautomatically.

As discussed above with reference to FIG. 1C, some playback devicesincorporate multiple microphones, for example as part of a microphonearray. In such examples, signals received from two or more of themicrophones may be processed to determine an angular component of alocation from which a signal is reflected. In some examples, twomicrophones each receive a signal containing at least one reflection ofa transmitted first sound signal. The two received signals are processedto determine a delay between the two received signals. For example, across-correlation may be determined between the two signals for a rangeof candidate delays, and the delay giving rise to a highest value of thecross-correlation is determined to be the delay between the two signals.Signals containing FMCWs are particularly suitable for suchapplications, as an FCMW can be arranged such that an autocorrelation ofthe FCMW (a cross correlation between the FCMW and a delayed copy of theFCMW) is uniquely maximized for a delay of zero. This is in contrast tosignals having fixed frequencies, in which signal offsets correspondingto a multiple of a wavelength may give rise to further autocorrelationmaxima.

FIG. 8 shows a top-down view in which a first sound signal transmittedby a playback device and containing a predetermined waveform isreflected from a person P in a playback environment. Two microphones 815a and 815 b, which have apertures separated by a distance d (asmeasured, in this example, between the centers of the apertures) eachreceive a respective sound signal containing a reflection of thetransmitted sound signal by the person P. The first microphone 815 areceives a sound signal corresponding to the reflected ray 802 a, andthe second microphone 815 b receives a sound signal corresponding to thereflected ray 802 b. A line BC passes through the center of the apertureof the second microphone 815 b, and is perpendicular to a line ABpassing through the centers of the apertures of the microphones 815 aand 815 b. An angle θ between the line BP (corresponding to thedirection of the reflected ray 802 b) and line BC is an angularcomponent of the location of the person P from the playback device. Inthis example, the distance BP between the person and the secondmicrophone 815 b is much greater than the distance d between themicrophones 815 a and 815 b, and the angle θ is therefore approximatelyequal to an angular component of the location of the person P from anypoint on the line segment AC between the two microphones 815 a and 815b. In many examples, the distance between two microphones of a playbackdevice is small (for example less than 10 mm or less than 5 mm), andtherefore it is expected that the distance from the playback device to alistener will be much greater than the distance between the twomicrophones.

The difference in length between the line segment BP and the linesegment AP is Δl, corresponding to the difference in path length betweenthe rays 802 a and 802 b. The difference Δl in path length is related toa delay Δt between the sound signals received by the two microphones 802a and 802 b by the equation Δl=vΔt, where v is the speed of sound in air(approximately 340 m/s under STP conditions). The angular component θ ofthe location of the person P from the playback device is given byθ=arcsin(Δl/d)=arcsin(vΔt/d), where arcsin denotes the inverse of thesine function for angles θ within the interval −π/2<θ<π/2 (measured inradians). By processing the sound signals received by the microphones815 a and 815 b, for example by determining a cross-correlation todetermine the delay Δt and then using the above equation to calculate θ,an angular component of the location P of the person may be determined.

In many situations, identifying a peak in signal amplitude as beingcaused by a direct reflection from a person is not straightforward, forexample due to reflections from other objects in a reverberantenvironment. In such cases, range-finding techniques and/or delayanalysis as described above may be less suitable for determining alocation of a person with respect to a playback device. An alternativemethod of determining a location of a person involves storing locationdata or calibration data associating stored sound signal data receivedwhen a person is at known locations within the playback environment. Anunknown location of a person is then determined to be the same as theknown location associated with the stored signal, based on acorrespondence between a received second sound signal and the storedsound signal. For example, a playback device may store location dataassociating each of a set of stored sound signals with a respectivelocation of a person. Upon receiving a second sound signal containingone or more reflections of a transmitted first sound signal, a locationof the person may be determined based on a best correspondence betweenthe received second sound signal and one of the stored sound signals. Acorrespondence can be measured according to any suitable metric, and alocation of a person may be determined only if a metric score for areceived second sound signal is higher than a predetermined thresholdvalue.

In some examples, configuration data is stored corresponding to a soundsignal received when no person is present in the playback environment.If a best correspondence with a received second signal is determined tobe with this configuration data, it is determined that no person is inthe playback environment. This method avoids a location of a personbeing erroneously determined when no person is in the playbackenvironment. Some examples may also apply the determination that aperson is unlikely to be present in the playback environment to takeappropriate action, such as ceasing or pausing audio reproduction byplayback devices associated with the playback environment.

FIG. 9 is a flow diagram of a calibration method 900 in which a playbackdevice (e.g., the playback device 410 of FIGS. 4 and 5 ) is prepared forbeing used to determine a location of a person using stored locationdata. The playback device transmits, at S910, a third sound signalcontaining a predetermined waveform, when a person is at a knownlocation relative to the playback device. In some examples, a user mayspecify a known location within a playback environment, for exampleusing a control device (e.g., the control device 130 a of FIG. 1H)connected via a network to the playback device. In other examples, auser may be directed to position themselves in a predetermined knownlocation, for example by providing an instruction to the user. Such aninstruction may be audible, transmitted by a playback device or anyother device in the playback system which is capable of audioreproduction. Such an instruction may be visual, for example using adisplay on the control device or other device in the playback system.Examples of known locations may include sitting on a particular chair,sitting in a particular position on a particular sofa, and standing in adoorway. Known locations may also be expressed in terms relative to aparticular playback device or group of playback devices, such as“center” or “off-center”, “left” or “right”, and so on. It will beappreciated that if a person is determined to be sitting in the chair,the person may, in fact, be standing in front of the chair. In this way,each known location is associated with a region of the playbackenvironment.

The playback device receives, at S920, a fourth sound signal containingat least one reflection of the third sound signal. Location data isstored, at S930, which includes data indicative of the fourth soundsignal and further indicative of an association between the fourth soundsignal and the known location of the person. In this example, thelocation data is stored in memory of the playback device itself. In someexamples, location data may be sent to a remote computing system forstorage, for example a computing system that is configured to process asecond sound signal to determine a location of a person. In someexamples, the location data may be sent to other devices on the playbacknetwork for storage, such as another playback device.

In the examples described above, a correspondence between two soundsignals may be determined in any suitable manner. For example, acorrespondence may be determined by comparing relative or absoluteamplitudes and/or timings of a highest predetermined number of localpeaks in the amplitude of the two sound signals. A metric score may thenbe determined in accordance with how closely matching the amplitudesand/or timings are, and/or the order in which the highest predeterminednumber of peaks occur in the signal. In another example, acorrespondence may be determined by computing a correlation between thereceived second sound signal and each of the stored second soundsignals.

In some examples in which location data is stored for determining alocation of a person, a playback device may be moved between differentpositions or orientations within a playback environment, or betweendifferent playback environments (for example, between different rooms ina house). In such examples, the playback device may store location datafor each of a set of orientations, where the location data stored foreach sound signal is associated with an orientation of the playbackdevice. FIG. 10 shows an example of a hierarchical data structure forstoring location data associated with different orientations of aplayback device. In this example, location data is stored for eightdifferent locations A-H of a person relative to the playback device.Locations A, B, and C are associated with a first orientation of theplayback device. Locations D, E, and F are associated with a secondorientation of the playback device, and locations G and H are associatedwith a third orientation of the playback device. In this example,orientation 1 and orientation 2 are different orientations of theplayback device within the same room of a house (i.e. within the sameplayback environment). Orientation 3 is an orientation of the playbackdevice within a different room of the house (i.e. within a differentplayback environment). Location data for each of the location includessignal data which is indicative of a received sound signal, and each setof stored signal data is associated with a respective location of aperson relative to the playback device.

In an example in which location data is associated with an orientationof a playback device, for example as shown in FIG. 10 , determining alocation of a person relative to the playback device may include firstdetermining an orientation of the playback device.

If, for example, the playback device is determined to be in orientation1, processing a received sound signal to determine the location of theperson may include comparing the received sound signal with signal data1.1, signal data 1.2, and signal data 1.3, but not with signal dataassociated with orientation 2 or orientation 3. This may increase theaccuracy with which a location of a person may be located, because fewersets of signal data are required to be compared with the received soundsignal. If, for example, determining a correspondence between thereceived second sound signal and a stored candidate signal involvesdetermining a best correspondence between the received second soundsignal and each set of stored candidate signals, comparing the receivedsignal with fewer stored candidate signals may result in fewer erroneousresults. Furthermore, comparing with fewer candidate signals reduces theamount of processing that needs to be performed in order to determinethe location of the person, resulting in faster determination of thelocation of the person.

Orientation can be determined in several ways. For example, anaccelerometer within the device may be used to determine whether thedevice is positioned horizontally or vertically, a stored variable maybe read to determine the orientation, or the orientation may bedetermined with reference to external devices, such as connection of theplayback device to a particular docking station. In some examples,determining an orientation of a playback device may include receiving auser input, for example using a control device associated with theplayback device. For example, a user may move the playback device from aknown orientation in a kitchen (orientation 1, for example) to a knownorientation in a living room (orientation 2, for example), and use thecontrol device to inform the playback device (or a computing systemperforming processing on behalf of the playback device) that theplayback device is now in orientation 2. In other examples, determiningan orientation of a playback device may include detecting a change inthe orientation of the playback device from the received sound signalitself. For example, a playback device may transmit a sound signalcontaining a predetermined waveform, and receive a sound signalcontaining reflections of the transmitted sound signal. The playbackdevice may determine that the received sound signal does not correspondto any of the stored signal data associated with orientation 1(including signal data corresponding to orientation 1 when no person ispresent in the kitchen), and search for signal data associated withorientation 2 and orientation 3. If a correspondence is determinedbetween the received signal and signal data associated with orientation2 (for example, signal data 2.2), the playback device is determined tobe in orientation 2.

In examples in which location data is associated with orientations of aplayback device, calibration of the playback device may include amodification of the routine of FIG. 9 in which the orientation of theplayback device is determined before or after the third sound signal istransmitted, and storing the location data includes associating thefourth sound signal with the determined orientation of the playbackdevice. The orientation of the playback device may be determined in anysuitable manner, as discussed above.

Returning now to the method 600 of FIG. 6 , a characteristic of audioreproduction by the playback device is selected at S640, based on thedetermined location of the person. As mentioned above, an example of acharacteristic of audio reproduction is a volume of the audioreproduction. Other characteristics of audio reproduction may also beselected, for example those described in detail with reference to FIG.11 below. In the example of FIG. 4 , the playback device 410 maydetermine that the listener 403 is located close to the playback device410, and accordingly may select a low volume for audio reproduction. Ata later time, the playback device 410 may determine that the listener403 is located further away from the playback device 410, and may selecta higher volume for audio reproduction. By periodically determining thelocation of the listener 413, and adjusting the volume in this way, theapparent volume of the audio reproduction experienced by the listener413 may be substantially constant as the listener moves throughout theplayback environment.

More generally, a playback device having performed the method 600 ofFIG. 6 to determine a first location of a person, and selected acharacteristic of audio production based on the determined firstlocation, may at a later time transmit a third sound signal containingthe predetermined waveform. The playback device may subsequently receivea fourth sound signal containing at least one reflection of the thirdsound signal. The playback device (or a computing system associated withthe playback device) may process the fourth sound signal to determine asecond location of a person, where the second location is different tothe first location. The playback device may then adjust thecharacteristic of audio reproduction based on the determined secondlocation of the person. In some examples, a playback device frequentlytransmits signals to determine a location of a person in this way,resulting in seemingly real-time adjustment of playback characteristicsas a listener moves around a playback environment. A playback device maytransmit signals for determining a location of a person at regular orirregular intervals, for example of at intervals greater than every 10seconds, at intervals greater than 1 second, or at intervals greaterthan every 0.1 seconds.

In some examples, a playback device may perform audio reproduction froma media source simultaneously with transmitting a first sound signalcontaining a predetermined waveform. The playback device maysubsequently receive a second sound signal containing at least onereflection of the first signal by a person, and process the receivedsecond signal to determine a location of the person relative to theplayback device without interrupting the audio reproduction. In thisway, characteristics of the audio reproduction may be selected and/oradjusted as the audio reproduction is performed, allowing the playbackdevice to adapt to the location of the person. In such examples, thesecond sound signal received by the playback device may includereflections of audio being played back by the playback device. Suchreflections will depend on the audio being played back, and therefore itis necessary to be able to distinguish reflections of the transmittedfirst sound signal from reflections of the audio being played back. Thismay be achieved, for example, by identifying the reflection of thepredetermined waveform in the received second signal. In some examples,the first signal and the audio may be generated and transmittedsimultaneously by the same transducer. In other examples, an additionaltransducer may be included for transmitting the first signal.

In some examples, a playback device may simultaneously perform audioreproduction and transmit an ultrasonic first sound signal containing apredetermined waveform for determining a location of a person.Processing the received second signal may then include passing thereceived second signal through a high-pass filter with a cutofffrequency just below the lowest frequency of the predetermined waveform(for example, around 20 kHz). This processing may substantially removereflections of the audio being played back by the playback device, asthe majority of the signal power in such audio is in the audible rangebelow the lowest frequency of the predetermined waveform. Usingultrasonic signals to determine a location of a person may also causelittle or no detrimental effect to the quality of audio reproduction, asthe ultrasonic signal is substantially inaudible to listeners, orinaudible to a majority of listeners.

shows an example of a playback environment 110 l occupied by a listener1103. The playback environment 110 l contains four playback devices 1110i, 1110 j, 1110 k, 1110 h, collectively referred to as playback devices1110, that can be configured for home theater as described above withreference to FIG. 1K. In this example, the playback devices 1110 belongto the same playback zone. A first playback device 1110 h comprises oneor more microphones and is configured to determine a location of aperson and to select a characteristic of audio reproduction inaccordance with the methods described herein. The playback environment110 l also includes a sofa 1105, a desk 1107, a television 1109, and adoorway 1111. The playback devices 1110 are bonded, and are henceconfigured to synchronously perform audio reproduction from a mediasource, as described above with reference to FIGS. 1A-1M. In addition todetermining a characteristic of audio production by the first playbackdevice 1110 a, the determined location of a person, for example thelistener 1103, may be used to select a characteristic of audioproduction by one or more of the other playback devices 1110. Forexample, the first playback device 1110 h may determine, by processingreflected sound signals as described above, that the listener 1103 islocated on the sofa 110 l, and configure the playback devices for hometheater operation by selecting a particular audio channel or channelsfor audio reproduction by the first playback device 1110 h Theparticular channel in this example may be a surround channel or a homecinema channel in which the first playback device 1110 h is responsiblefor a particular part of the audio reproduction, and each of the otherplayback devices 1110 i, 1110 j, 1110 k is responsible for a respectivepart of the audio reproduction. In this example, a respective surroundchannel is selected for each of the playback devices 1110 j, 1110 k anda Low Frequency Effects (LFE) channel is selected for the playbackdevice 1110 i.

At a later time, after having been located at the sofa 1105, thelistener 1103 may walk to the desk 1107. The first playback devicedetermines, by processing reflected sound signals as described above,that the person is located at the desk 1107. Accordingly, a differentchannel for audio reproduction by the first playback device may beselected. The different channel may be, for example, left and rightstereo channels and the playback devices 1110 may be configured forstereo reproduction. Different channels may also be selected for audioplayback by the other playback devices 1110, for example left and rightstereo channels may be selected for the playback devices 1110 j or 1110k respectively. Alternatively, when the person is determined to belocated at the desk 1107, the playback devices 1110 j and 1110 k may bereconfigures so that they are not part of the playback zone and no audioreproduction is performed. It will be appreciated that the embodimentdescribed with reference to FIG. 11 is exemplary, and other arrangementsof playback devices, and accordingly other configurations of audiochannels are possible without departing from the scope of the invention.

A further example of a characteristic of audio reproduction that may beselected based on a determined location of a person is delay of audioreproduction by a first playback device relative to corresponding audioreproduction by another playback device bonded to the first playbackdevice. In the embodiment of FIG. 11 , the playback devices 1110 j, 1110k may be configured to synchronously perform audio reproduction onrespective surround sound channels. The listener 1103 may be determinedto be located closer to the playback device 1110 j than to the playbackdevice 1110 k. The playback device may then select a respective delay ofaudio reproduction by the playback devices 1110 j and 1110 k. Byselecting a delay in this way, audio from different playback channelsarrives at the listener 1103 substantially in phase, improving thelistening experience for the listener 1103.

In some examples, a bonding, pairing, or grouping of playback devicesmay be altered dynamically based on a determined location of a person.In the example of FIG. 11 , if a person is determined to be located inor near the doorway 1111, playback devices in the next room, whichbelong to a different playback zone to the playback devices 1110, may begrouped with the playback devices 1110 so that the playback devices inthe two neighboring rooms may perform audio reproduction synchronously.The person may therefore experience a substantially seamless transitionas the person moves from the playback environment 1111 to theneighboring playback environment. Alternatively, bonding or pairing ofplayback devices within a single playback environment may be altereddepending on a determined location of a person. In the example of FIG.11 , the playback devices 1110 h, 1110 i, 1110 j, 1110 k, may only bemutually bonded to form a playback zone when a person is determined tobe located on the sofa 1103. Otherwise, the playback devices may eachperform audio reproduction independently, or one or more subsets of theplayback devices may form respective playback zones.

In some examples, a playback device arranged to determine a location ofa person according to the methods described herein, may receive an audiosignal including a spoken input, and may associate the spoken input withthe determined location of the person. By associating a spoken inputwith a determined location of a person, the playback device (or acomputing system processing the spoken input received by the playbackdevice) may ascertain additional information relating to the spokeninput. For example, the playback device may receive a spoken input froma person which may use a location-based context to interpret the input.This may be an explicit statement, an utterance such as “near me”,“where I am” or implicit in the command, such as an utterance to “turndown the volume” which may use a location to determine for whichplayback devices volume is turned down. Other examples are possible andin general a spoken input may be associated with a determined locationof the person. The playback device may, for example, adjust acharacteristic of audio reproduction in response to receiving the spokeninput. Adjusting a characteristic of audio reproduction in response toreceiving a spoken input may prevent unwanted adjustments ofcharacteristics, for example if a person temporarily moves from the sofa1105 of FIG. 11 whilst the playback devices 1110 are configured in homecinema mode. Alternatively, the spoken input may include a voice commandto control audio reproduction by the playback device. For example, aplayback device may at a certain time be in an idle mode and notperforming audio reproduction, and may receive an audio signal includinga spoken input from a person saying, “turn the music on”. The playbackdevice may associate the spoken input with a determined location of theperson, and begin audio reproduction with characteristics selected basedon the determined location of the person. In a further example, aplayback device may receive an audio signal from a person saying, “turnthe music down near me”. The playback device may reduce the volume ofaudio reproduction by one or more playback devices near the determinedlocation of the person, but not reduce the volume of audio reproductionby playback devices not near the determined location of the person.

In some examples, a spoken input may include a voice command to controla further device, for example a further device other than a playbackdevice. In response to receiving a spoken input, a playback device maysend a control signal to the further device dependent on a determinedlocation of a person. For example, a playback device arranged todetermine a location of a person according to the methods describedherein may be connected via a network to one or more further devices,such as a thermostat (e.g., NEST® thermostat), an illumination device(e.g., a PHILIPS HUE® lighting device), or a further media playbackdevice (e.g., a Sonos® playback device). The playback device may receivean audio signal containing a spoken input including a voice command tocontrol one of the further devices.

In one example, the listener 1103 in FIG. 11 may initially be located onthe sofa, watching a film on the television 1109. The playback devices1110 may be configured to perform audio reproduction in a home cinemamode, and lighting in the playback environment 110 l may be dimmed. Thelistener 1103 may subsequently stop watching the film, and walk to thedesk 1107 to do some work. The playback device 1110 a may then determinethat the listener 1103 is located at the desk 1107. The playback device1110 a may receive a spoken input from the listener containing a voicecommand saying, “turn the lights on over here”. The playback device 1110a may associate the spoken input with the determined location of theperson (at the desk 1107) and accordingly send a control signal to anillumination device controlling the lighting in the playback environment110 l. The illumination device may, in response to receiving the controlsignal, turn on a light near the desk 1107. The illumination device mayfurther turn off the lights near the sofa, or alternatively may undimthe lights near the sofa.

IV. Conclusion

The above discussions relating to playback devices, controller devices,playback zone configurations, and media content sources provide onlysome examples of operating environments within which functions andmethods described below may be implemented. Other operating environmentsand configurations of media playback systems, playback devices, andnetwork devices not explicitly described herein may also be applicableand suitable for implementation of the functions and methods.

The above embodiments are to be understood as illustrative examples ofthe invention. Further embodiments of the invention are envisaged. Forexample, multiple playback devices may be connected via a network withina smart home environment, each being configured to determine a locationof a person within a respective portion of the environment, for examplea particular room in the smart home, and to send control signals todevices within the respective portion.

The description above discloses, among other things, various examplesystems, methods, apparatus, and articles of manufacture including,among other components, firmware and/or software executed on hardware.It is understood that such examples are merely illustrative and shouldnot be considered as limiting. For example, it is contemplated that anyor all of the firmware, hardware, and/or software aspects or componentscan be embodied exclusively in hardware, exclusively in software,exclusively in firmware, or in any combination of hardware, software,and/or firmware. Accordingly, the examples provided are not the onlyways) to implement such systems, methods, apparatus, and/or articles ofmanufacture.

Additionally, references herein to “embodiment” means that a particularfeature, structure, or characteristic described in connection with theembodiment can be included in at least one example embodiment of aninvention. The appearances of this phrase in various places in thespecification are not necessarily all referring to the same embodiment,nor are separate or alternative embodiments mutually exclusive of otherembodiments. As such, the embodiments described herein, explicitly andimplicitly understood by one skilled in the art, can be combined withother embodiments.

The specification is presented largely in terms of illustrativeenvironments, systems, procedures, steps, logic blocks, processing, andother symbolic representations that directly or indirectly resemble theoperations of data processing devices coupled to networks. These processdescriptions and representations are typically used by those skilled inthe art to most effectively convey the substance of their work to othersskilled in the art. Numerous specific details are set forth to provide athorough understanding of the present disclosure. However, it isunderstood to those skilled in the art that certain embodiments of thepresent disclosure can be practiced without certain, specific details.In other instances, well known methods, procedures, components, andcircuitry have not been described in detail to avoid unnecessarilyobscuring aspects of the embodiments. Accordingly, the scope of thepresent disclosure is defined by the appended claims rather than theforegoing description of embodiments.

When any of the appended claims are read to cover a purely softwareand/or firmware implementation, at least one of the elements in at leastone example is hereby expressly defined to include a tangible,non-transitory medium such as a memory, DVD, CD, Blu-ray, and so on,storing the software and/or firmware.

The invention claimed is:
 1. A media playback system comprising: a firstplayback device comprising a first one or more processors, a first oneor more audio transducers, and a first one or more microphones; a secondplayback device comprising a second one or more processors, a second oneor more audio transducers and a second one or more microphones; one ormore computer-readable media storing instructions that, when executed bythe first one or more processors and/or the second one or moreprocessors, cause the media playback system to perform operationscomprising: transmitting, by the first one or more audio transducers, afirst sound signal comprising a predetermined waveform; receiving, viathe first one or more microphones, a second sound signal comprising areflection of the first sound signal; processing the second sound signalto determine a first location of a person relative to the first playbackdevice; transmitting, by the second one or more audio transducers, athird sound signal comprising a predetermined waveform; receiving, viathe second one or more microphones, a fourth sound signal comprising areflection of the third sound signal; processing the fourth sound signalto determine a second location of the person relative to the secondplayback device; and selecting a characteristic of audio reproduction bythe first and second playback devices based on the determined firstlocation and second location, wherein the characteristic of audioreproduction comprises a relative delay in audio playback between thefirst and second playback devices.
 2. The media playback system of claim1, wherein the operations further comprise playing back audio via thefirst and second playback device in synchrony with one another.
 3. Themedia playback system of claim 1, wherein the characteristic of audioreproduction comprises grouping or ungrouping the first and secondplayback devices together for synchronous playback.
 4. The mediaplayback system of claim 1, wherein processing the second and fourthsound signals further comprises disregarding a portion of the second andfourth sound signals corresponding to self-responses of the first andsecond playback devices, respectively.
 5. The media playback system ofclaim 1, wherein the first and second playback devices are bonded withadditional playback devices so as to synchronously perform audioreproduction with the first and second playback devices, and wherein theoperations further comprise selecting a characteristic of audioreproduction by each of the additional playback devices based on thedetermined locations of the person.
 6. The media playback system ofclaim 1, wherein the first sound signal and the third sound signal eachhave a frequency of greater than 20 kHz.
 7. A method comprising:transmitting, by a first one or more audio transducers of a firstplayback device, a first sound signal comprising a predeterminedwaveform; receiving, via a first one or more microphones of the firstplayback device, a second sound signal comprising a reflection of thefirst sound signal; processing the second sound signal to determine afirst location of a person relative to the first playback device;transmitting, by a second one or more audio transducers of a secondplayback device, a third sound signal comprising a predeterminedwaveform; receiving, via a second one or more microphones of a secondplayback device, a fourth sound signal comprising a reflection of thethird sound signal; processing the fourth sound signal to determine asecond location of the person relative to the second playback device;and selecting a characteristic of audio reproduction by the first andsecond playback devices based on the determined first location andsecond location, wherein the characteristic of audio reproductioncomprises a relative delay in audio playback between the first andsecond playback devices.
 8. The method of claim 7, further comprisingplaying back audio via the first and second playback device in synchronywith one another.
 9. The method of claim 7, wherein the characteristicof audio reproduction comprises grouping or ungrouping the first andsecond playback devices together for synchronous playback.
 10. Themethod of claim 7, wherein processing the second and fourth soundsignals further comprises disregarding a portion of the second andfourth sound signals corresponding to self-responses of the first andsecond playback devices, respectively.
 11. The method of claim 7,wherein the first and second playback devices are bonded with additionalplayback devices so as to synchronously perform audio reproduction withthe first and second playback devices, and wherein the method furthercomprises selecting a characteristic of audio reproduction by each ofthe additional playback devices based on the determined locations of theperson.
 12. The method of claim 7, wherein the first sound signal andthe third sound signal each have a frequency of greater than 20 kHz. 13.One or more tangible, non-transitory computer-readable media storinginstructions that, when executed by one or more processors of a mediaplayback system comprising a first playback device and a second playbackdevice, cause the media playback system to perform operationscomprising: transmitting, by a first one or more audio transducers ofthe first playback device, a first sound signal comprising apredetermined waveform; receiving, via a first one or more microphonesof the first playback device, a second sound signal comprising areflection of the first sound signal; processing the second sound signalto determine a first location of a person relative to the first playbackdevice; transmitting, by a second one or more audio transducers of thesecond playback device, a third sound signal comprising a predeterminedwaveform; receiving, via a second one or more microphones of a secondplayback device, a fourth sound signal comprising a reflection of thethird sound signal; processing the fourth sound signal to determine asecond location of the person relative to the second playback device;and selecting a characteristic of audio reproduction by the first andsecond playback devices based on the determined first location andsecond location, wherein the characteristic of audio reproductioncomprises a relative delay in audio playback between the first andsecond playback devices.
 14. The computer-readable media of claim 13,wherein the operations further comprise playing back audio via the firstand second playback device in synchrony with one another.
 15. Thecomputer-readable media of claim 13, wherein the characteristic of audioreproduction comprises grouping or ungrouping the first and secondplayback devices together for synchronous playback.
 16. Thecomputer-readable media of claim 13, wherein processing the second andfourth sound signals further comprises disregarding a portion of thesecond and fourth sound signals corresponding to self-responses of thefirst and second playback devices, respectively.
 17. Thecomputer-readable media of claim 13, wherein the first and secondplayback devices are bonded with additional playback devices so as tosynchronously perform audio reproduction with the first and secondplayback devices, and wherein the operations further comprise selectinga characteristic of audio reproduction by each of the additionalplayback devices based on the determined locations of the person.